Cellular phones and other like products often use two devices for generation of sound to be heard by a user. A transducer acts as a receiver. A separate unit, such as a buzzer, functions to provide “alert signals” to the user. Alert signals include ring tones when a call is being received, system signals such as to indicate a low battery, and other sounds such as tones for electronic games. These alert tones generally need to be of sufficient volume to be heard in a noisy environment. In some cases the buzzer may instead be a second speaker. Similar functions may be provided by the two speakers in this configuration: One speaker generally acts to provide sound for a user to hear in a phone call, and the other speaker provides sound for alert functions. This type of design, involving a receiver or earpiece speaker, and a separate, high-output, loudspeaker allows for appropriate sound output levels and frequency responses to be set for handheld use and use at a distance, respectively.
In some designs of clamshell-style and jackknife-style mobile handsets it is desirable to have sound projected from the handset when the handset is in the open, extended position and when the handset is in the closed position. In addition, many modern mobile handsets offer a type of handheld “walkie-talkie” type of audio known as Push-to-Talk (PTT). One reason for PTT's popularity is that as a matter of convenience a user need not hold the handset close to the ear. There are technical requirements, however, placed on mobile handsets that result from PTT functionality.
In order to provide acceptable audio levels at a distance of up to arm's length away from the ear, even, for example, in noisy environments such as construction sites, factories, highways, or city streets, PTT devices must be capable of producing very high sound pressure levels without excessive distortion. To do so, a relatively large acoustic transducer is needed. Further, in some mobile handsets having a clamshell design or jack-knife design with a flip attached to a base, the handset opens and closes around a hinge near the midpoint of the handset. Audio is preferably clearly audible in either position of the flip because users often want to access the PTT function without having their phone in the open position. Some mobile handsets with PTT functionality also include speakerphone capability that allows use without holding the handset, which may require clear audio at distances greater than arms' length.
Accordingly, there is a need for a mobile handset configuration that provides appropriately adjusted acoustic levels and frequency characteristics at the handset's earpiece via the use of a traditional acoustic receiver unit, provides polyphonic and/or loudspeaking functionality using a separate, remotely mounted loudspeaker, and directs the audio alert and loudspeaker acoustic output generally toward a user in order to provide clear audio whether in the open or closed position. There is also a need for the handset configuration to provide speakerphone capability.